1. Field of the Invention
The invention relates to a light guide for a lighting and/or signaling module, notably for a vehicle. The invention also relates to a support for such a light guide. The invention also relates to a lighting and/or signaling module comprising such a support and possibly such a guide arranged on the support.
2. Description of the Related Art
In the field of motor vehicle lighting and signaling, it is becoming increasingly commonplace for use to be made of optical waveguides. An optical waveguide is, very schematically speaking, an elongate element of transparent material, generally in the form of a cylinder. Near one of the ends of the guide, referred to as the input face of the guide, there is (or are) one (or more) light sources, for example a small-size light source of the light-emitting diode type: the rays of light emitted by this source travel by total reflection along the length of the guide toward its opposite end referred to as the terminal face of the guide. Some of the rays of light passing along the guide will emerge via the face referred to as the front face of the guide because of the presence of reflective elements arranged on the face, opposite to the previous face, referred to as the rear face of the guide. These reflective elements consist for example of prisms, forming reflective facets.
The guide thus emits light along its entire length. It has the advantage of being able to adopt very varied geometric shapes, of being straight or curved into an arc of a circle, and of conveying a lighting surface even to somewhat inaccessible regions of the vehicle light or headlamp. It thus makes a significant contribution toward the style of the light or of the headlamp. Depending on the overall shape of the guide or even on the length thereof, it may prove difficult to attach to the light or headlamp of the vehicle, particularly when there is a need to ensure that the guide maintains a uniform appearance over the entirety of its visible length.
Patent document DE 10 2007 010 023 A1 discloses a signaling device of the flashing indicator type intended to be incorporated into an external rear-view mirror of a vehicle. It comprises a light guide consisting of two elements which are elongate in two parallel longitudinal directions and connected to one another by a central part running along the elements. Lugs for attaching the guide to a support are provided at one of the two ends thereof. The support comprises two longitudinal enclosures which are parallel and of U-shaped overall section. Each longitudinal element of the guide is housed in one of these enclosures. The guide is thus held only by its two ends, the two parallel longitudinal elements being held in their respective enclosures with their exterior surface distant from the surface of the enclosure. This way of attaching the light guide is practicable for guides of short length, and in particular for multiple guides of greater rigidity, the issue being that for simple light guides, there is a risk that such attachment may pose problems, notably problems of uncontrolled contact between the surface of the guide and that of the enclosure.
U.S. Publication No. U.S. 2005/0254253 A1, now U.S. Pat. No. 6,984,062, discloses a vehicle headlamp equipped with two circular signaling modules, each one surrounding a lighting module. Each of these signaling modules comprises a longitudinal light guide of circular overall shape. It is housed in an enclosure, likewise circular and comprising notches intended to collaborate with fixing tabs extending rearward from the rear face of the guide. These tabs are generally flexible and provided with a positive-contact surface able to collaborate with the edge of the corresponding notch of the support. The enclosure is generally circular and of generally rectangular cross section open in such a way as to be able to accept the light guide the corresponding cross section of which is likewise approximately rectangular. The closed end of the enclosure comprises a series of openings intended to let out the rays of light emitted by the light source positioned behind the light guide. This module is fairly advantageous from the standpoint of its simplicity of construction. The fixing tabs do, however, influence the transmission of light. This effect is not excessively troublesome in the module configuration described therein because the enclosure has four openings feeding the guide with light and these are distributed about its circumference. The non-uniformities caused by the fixing tabs are thus reduced. In the case of a light guide fed only via one of its ends, or even by both, this solution does generate non-uniformities that do present a problem. In addition, this type of mounting requires contact between the rear face of the guide and the surface of the enclosure. The rectangular cross section of the guide and of the enclosure also constitute a limitation which may prove penalizing for other applications.